1. Department of Chemistry, Technical and Agricultural University, Seminaryjna 3, PL-85-326 Bydgoszcz, Poland, Department of Chemistry, University of Jyväskylä, P.O. Box 35, FIN-40351 Jyväskylä, Finland, and Department of Chemistry, University of Warsaw, Pasteura 1, PL-02-093 Warsaw, Poland